Browsing by Author "Roman, Manuel San"

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    Holocene interactions between marine nomads and their coastal landscape in the Strait of Magellan, southern Patagonia: Ichthyoarchaeological and isotopic evidence
    (2024) Torres, Jimena; Gonzalez, Karina; Santana-Sagredo, Francisca; Andrade, Claudia; Roman, Manuel San; Harrod, Chris
    Marked environmental changes occurred in the southern Patagonian archipelago during the middle and late Holocene, including increased variability in glacial coverage and marine productivity. Those changes likely impacted the lives of marine hunter gatherers and their exploitation of faunal resources. Here, we examine temporal trends in fishes captured during the mid- and late Holocene, including variation in stable isotope values (delta 13C and delta 15N) of the most commonly exploited taxa to explore potential changes in fishing strategies due to environmental and cultural causes. We examined fish remains from eight archaeological sites and cultural periods in the Strait of Magellan. The ichthyoarchaeological results indicate drastic changes in the assemblages of fishes captured, with demersal species dominating catches before 2700 cal. yr BP and a subsequent switch to coastal fishes associated with subtidal kelp forests afterwards until 500 cal yr BP, both in the Strait of Magellan and adjacent seas. Although limited by sample sizes, our isotopic data show little obvious variation in Eleginops maclovinus over the different periods. However, Patagonotothen sp. and Salilota australis displayed significant isotopic shifts during the Holocene, but followed distinct, taxon-specific trajectories. This suggests that responses to the late Holocene environmental changes differed between species. This study also contributes to the baseline ecological information prior to the impact of modern industrial fishing practices with data from native fishes that are important components in kelp forests (Macrocystis pyrifera) ecosystems of the sub-Antarctic region.
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    Resolving the paradox of conflicting glacial chronologies: Reconstructing the pattern of deglaciation of the Magellan cordilleran ice dome (53-54°S) during the last glacial - interglacial transition
    (2024) Mcculloch, Robert D.; Bentley, Michael J.; Fabel, Derek; Fernandez-Navarro, Hans; Garcia, Juan-Luis; Hein, Andrew S.; Huynh, Carla; Jamieson, Stewart S. R.; Lira, Maria-Paz; Luethgens, Christopher; Nield, Grace A.; Roman, Manuel San; Tisdall, Eileen W.
    Raised shorelines and associated lacustrine sediments in the central Estrecho de Magallanes (Strait of Magellan) have been interpreted as products of cordilleran glaciers impounding a large proglacial lake and preventing drainage to the South Pacific and Southern Ocean during the Late glacial between c. 15.0 and 12.0 cal ka BP. However, a growing body of glacial geological evidence points towards an earlier retreat of the Magellan cordilleran ice dome, insufficient to dam lakes at that time. We critically re-evaluate the extant evidence for the c. 15.0-12.0 cal ka BP lake, here named 'Lago Kawesqar', and provide further sedimentological and chronological evidence for its existence. We also provide new cosmogenic surface nuclide dating of erratic and bedrock samples collected from extensive field campaigns that confirm the rapid and widespread retreat of the Magellan ice fields to the inner fjords of the Fuegian archipelago by c. 16.0 ka. To resolve the apparent paradox between these two lines of evidence we propose that glacial isostatic adjustment led to a topographic barrier to lake drainage rather than an ice dam. We use Glacial Isostatic Adjustment modelling to demonstrate that rapid isostatic recovery following the early deglaciation after c. 17.0 cal ka BP likely led to elevation of the present shallow south-western coastal margin of the Fuegian archipelago. Final drainage of Lago Kawesqar was probably caused by neotectonic subsidence of the same margin along the boundary of the South American - Scotia tectonic plates at c. 12.0 cal ka BP.